By Marcel Beijk
Coronary bifurcation lesions make up 15% to 20% of percutaneous coronary interventions and remain a challenge for cardiologists due to the complexity of the lesions themselves and the increased frequency of associated adverse events. Several studies have shown that drug-eluting stents effectively reduce restenosis rates in the main branch, but restenosis still occurs in the side branches, even when multiple stents are used. In patients with bifurcation lesions, drug-eluting stents may be associated with an increased risk of stent thrombosis, and, for this reason, it is necessary to identify alternative treatment options that are viable for this difficult-to-treat indication.
Bifurcation lesions are more complex to treat because of the bifurcation anatomy itself, as well as the possibility of plaque shift from the main branch into the side branch that can occur during treatment. Frequently, physicians are thus required to address both branches. Techniques for treating these lesions, whether using one or two stents, focus on optimal angiographic result and/or optimal flow.
With recent advances in stent technology, interventional cardiologists are now finding that there are alternatives to drug-eluting and bare metal stents that may prove significant to this patient population. Specifically, a technology that promotes the accelerated healing of the vessel wall has the potential to address the increased risk of stent thrombosis. One such innovation that offers particular promise for treating these lesions is the Genous stent (OrbusNeich). The Genous stent employs a unique endothelial progenitor cell (EPC) capture technology that uses CD34+ antibodies to attract circulating EPCs to the stent surface, driving rapid endothelialisation, thus inhibiting thrombosis risk.
The potential for the use of EPC capture technology in addressing bifurcation lesions was recently observed in a study that was conducted at the Academic Medical Center in Amsterdam. Results were published in the journal Atherosclerosis. This study compared the Genous stent to a bare metal stent with the same stent platform as the Genous stent. The provisional T-stenting technique was used for treatment of bifurcation lesions, and the benefit of this added pro-healing technology was evaluated.
The chief benefit of the Genous stent relative to drug-eluting stents is that Genous does not impede the natural healing response in patients. After the circulating EPCs are immobilised on the Genous stent surface, these cells rapidly differentiate into a functional endothelial layer. This accelerated arterial repair mediated by the EPC capture may effectively inhibit stent-related thrombus formation and neointimal hyperplasia, which has a distinct benefit in this patient group.
The study showed that there was a lower incidence of stent thrombosis in the Genous group compared to bare metal stents and observed a reduction in clinical events at one year follow-up compared to the control population. The study’s primary endpoint was a composite of cardiac death, myocardial infarction and target lesion revascularisation. At one year follow-up, the cumulative rate of the primary endpoint was 17.2% in the bare metal stent group and only 12.4% in the Genous group. These results from the Genous-treated group are comparable to those associated with drug-eluting stents in other studies.
In addition, the definite or probable stent thrombosis rate was higher in the bare metal stent group, namely 3.4%, when compared with 1.7% in the Genous group.
Of all types of bifurcation lesions though, those of the left main still remain the most difficult to treat. Treatment in this subgroup of patients carries a higher risk of complications. This type of lesion was not addressed in the previously mentioned study, though it remains an area of great interest. For other types of bifurcation lesions where stent implantation is appropriate, Genous is a promising alternative to drug-eluting stents when thrombosis risk is a cause for concern.
Marcel Beijk, Academic Medical Center, University of Amsterdam, The Netherlands.